1. Field of the Invention
This invention relates to a positioning structure of a flexible printed circuit for a pick-up used in a disc drive and a pick-up assembly used in a disc drive. In particular, this invention relates to a positioning structure of a flexible printed circuit which is connected to an optical pick-up used in a disc drive to input and output various electrical signals to and from the optical pick-up, and also relates to an optical pick-up assembly which includes an optical pick-up and a flexible printed circuit connected to the optical pick-up.
2. Description of the Prior Art
Disc drives such as CD-ROM drives are provided with an optical pick-up for reading out information recorded on a CD-ROM, and the disc drives read out (playback) information which is recorded on the disc through a great number of pits formed spirally on the disc using the optical pick-up. Further, in CD-R drives, in addition to the playing back operation, it is further possible to write new information on the disc using the optical pick-up.
In these disc drives, there are provided a turntable on which a disc is placed and which is rotated by a motor, an optical pick-up (hereinafter, referred to as xe2x80x9cpick-upxe2x80x9d) for reading out signals recorded on the disc placed on the turntable, and a sliding feed mechanism for moving the pick-up in a radial direction of the disc, and they are provided on a chassis of a main body of the disc drive. Further, below the chassis, there is arranged a printed circuit board. On the printed circuit board, there are provided electrical circuits and electronic parts and the like for processing signals read out from the disc by the pick-up and carrying out servo controls for the pick-up. The pick-up and the printed circuit board are connected with each other with a flexible printed circuit which passes through an opening formed in the chassis.
In this flexible printed circuit, there are provided a plurality of conductors for supplying signals reproduced by the pick-up and other various signals for focusing servo control and tracking servo control and the like, thus it is formed so as to have a relatively large width. The end portion of the flexible printed circuit is connected to a predetermined connector provided on the printed circuit board, and then electrically connected to the electrical circuits and the electronic parts through the connector.
Meanwhile, the optical pick-up moves in the radial direction over a wide range when the disc drive is turned on to move the pick-up for initialization or when track jump is performed upon seek operation. When the pick-up moves in this way, the flexible printed circuit also moves with changing its form within the chassis, and at such a time if the flexible printed circuit abuts the disc, the disk is liable to be damaged. Further, if such a flexile printed circuit is caught by any part or component, there is a case that the pick-up can not move further or the flexible printed circuit is damaged. Furthermore, there is a case that an excessive load is applied to the connecting portion between the flexible printed circuit and the optical pick-up due to the movement of the pick-up, and such a load may result in a connection failure. Moreover, when the pick-up moves toward the center of the disc, the flexible printed cable is somewhat pulled, and if such a pulling force is transmitted to the connecting part on the printed circuit board, there may arise a loosening of the connector and a connection failure.
Further, since it is required for the pick-up to be moved in the radial direction of the disc with a very high accuracy during disc playing back operation being carried out, it is required for the flexible printed circuit not to affect such accurately controlled movement of the pick-up.
For these reasons, in the conventional disc drives, in order to keep the length of a portion of the flexible printed circuit that lies within the space in the chassis in a constant length and avoid the pulling force caused by the movement of the pick-up from being transmitted to the connector on the printed circuit board, a vinyl tape or the like is wound around a prescribed portion of the flexible printed circuit to position it with respect to the chassis.
However, in such a method using the tape wound around the flexible printed circuit, there is a case that the position of the wound tape is displaced or the wound tape is loosened due to the pulling force caused by the movement of the pick-up.
Further, in the conventional structure, there is another problem in that dust or dirt enters into the space above the chassis in which the optical pick-up or the like are provided from the opening formed in the chassis due to a sucking force (negative pressure) created by high speed rotation of the disc during the operation, which results in malfunction of the optical pick-up if the dust is attached to the objective lens.
Further, in the method using the wound tape, there still remain the problem that a load is applied to the connection portion between the pick-up and the flexible printed circuit by the movement of the pick-up.
The present invention has been made in view of the problems in the positioning structure of the flexible printed circuit used in the prior art disc drives. Accordingly, it is a main object of the present invention to make it possible to position the flexible printed circuit with respect to the chassis easily and reliably.
Another object of the present invention is to prevent dust or dirt from entering into the space above the chassis from the side of the printed circuit board though the opening through which the flexible printed circuit extends.
Other object of the present invention is to prevent a load from being applied to the connecting part between the flexible printed circuit and the pick-up by the movement of the pick-up and give an ideal curved form to the flexible printed circuit so as not to disturb the movement of the pick-up.
In order to achieve these objects, the present invention is directed to a positioning structure of a flexible printed circuit for a pick-up used in a disc drive, which comprises:
a turntable for supporting a disc thereon, the turntable being driven by a motor;
a pick-up at least for reproducing information recorded on the disc to be supported on the turntable, the pick-up being movable in a radial direction of the disc;
a chassis provided with the turntable and the pick-up, and the chassis having an opening and a positioning means provided at or near the opening;
a printed circuit board arranged below the chassis and provided with electrical circuits for inputting and outputting electrical signals to and from the pick-up; and
a flexing printed circuit for connecting the pick-up to the printed circuit board through the opening of the chassis, wherein the flexible printed circuit is formed with an engaging means to be engaged with the positioning means.
According to the present invention having the structure as described above, even when the optical pick-up moves over large range in the radial direction of the disc due to an initializing operation at starting or a track jumping operation, a pulling force caused by the movement of the optical pick-up is not transmitted to the connector on the printed circuit board since the pair of the engaging portions of the flexible printed circuit are in engagement with the protruding parts formed on the supporting plate, respectively.
In the present invention, it is preferred that the positioning structure of the flexible printed circuit further includes a closure member for covering the opening of the chassis. In this case, it is preferred that the closure member is removably attached to the chassis. By provision of such a closure member, it is possible to prevent dust or dirt from entering into the space above the chassis from the side of the printed circuit board through the opening due to a sucking force created by the high speed rotation of the disc.
Further, it is preferred that the positioning means is formed from a pair of protruding portions provided near said opening, and the engaging means of said flexible printed circuit is formed from a pair of concave portions integrally formed on the opposite sides of the flexible printed circuit perpendicular to the longitudinal direction of the flexible printed circuit so as to engage with the protruding portions, respectively. In this way, it is possible to position the flexible printed circuit with respect to the chassis easily and reliably and to keep the length of the portion of the flexible printed circuit which lies on the upper side of the chassis constant.
Further, it is also preferable to further comprise a regulating member provided at a connection part of the flexible printed circuit and the pick-up for regulating an extending direction of the flexible printed circuit from the pick-up so as to give a desired curved form to the flexible printed circuit. In this way, it is possible to avoid a load is applied to the connecting part between the pick-up and the flexible printed circuit by the movement of the pick-up as well as to provide the flexible printed circuit an ideal curved form which does not disturb the movement of the pick-up.
Other objects, structures and advantages of the present invention will be apparent when the following detailed description of the preferred embodiment will be considered taken in conjunction with the accompanying drawings.